The field of the invention relates to the display of scenes or scenery, more especially in night viewing conditions, by implementing easy-to-handle and transportable means such as binoculars.
Conventionally, under the conditions referred to, a scene is observed by means of a telescope, a periscope or a pair of binoculars which are appreciated for their quality of luminosity.
More recently, head-up type display devices have appeared. These devices enable the superimposition, on the optical image, of another image displaying additional information elements in the visor (for example, information elements pertaining to the time elapsed, localization on a map, reference numbers etc.) related to the optical image. The additional information elements generally come from a cathode-ray tube or a liquid crystal screen and are transmitted by optic fibers and/or through adapted optical elements (such as mirrors, lenses, semi-reflector mirrors etc.) up to the main optical axis of the visor. An assembly such as this is described, for example, in the U.S. Pat. No. 4,915,487. In this document, the additional information elements are carried through one of the two optical channels of a pair of binoculars. For night vision, provision is made in conventional systems for the activation of a light intensifier tube. In general, the day/night optical systems such as periscopes, episcopes, etc. have light intensifier tubes such as these positioned in an path that can be switched over if necessary (see for example the patent FR 2 578 062).
Furthermore, there are day-and-night observation devices, known notably from the patent GB 2 149 141, that integrate an infrared imaging system for night vision. Such systems have the advantage of giving an image with a quality that is far higher than that given with light intensifiers alone.
However, infrared imaging systems are cumbersome, difficult to handle and complicated.